This invention relates to die casting machines and in particular to a system including a die casting machine of the balanced, dual movement type that incorporates two pairs of spaced, parallel cylinder assemblies each of which support a mold half, the pistons of the cylinders being secured to the machine frame and the cylinders moving thereon.
In a conventional die casting machine a frame is provided and a fixed or stationary plate upon which one-half of the mold for making the part is mounted on the frame. The other half of the mold is mounted upon a moving plate which allows the cast part to fall out of the machine when in the open position and the moving plate is clamped shut with sufficient force to contain the molten metal while the mold is being filled. In operation, the part separates from the half mold on the fixed plate (the cover half) and is retained on the half mold of the moving plate (the ejector half) as it moves open following solidification of the molten metal which was injected into the mold cavity. The part which was retained on the moving or ejector half of the mold must then be ejected from it to fall out or be transferred out of the machine. The one-sided motion described above is one of the major causes for the various and complicated types of automatic part-transfer mechanisms associated with conventional casting machines which have been retrofitted with some sort of part-transfer. The same problem then arises as the part is indexed to a secondary operation such as trimming wherein a similar one-sided machine is used. The part-transfer carrier is required to have both an indexing function and a lateral movement to match the plate closing and opening stroke as the part is brought into a fixed position for the desired operation.
This conventional form of machine was greatly improved upon by the machine shown in the U.S. Pat. No. to Perrella, 4,013,116 which issued on Mar. 22, 1977. This machine is much simpler than conventional devices in that the part was cast, indexed and removed from the machine for trimming without any lateral movement of the part. During processing the part is in a fixed plane and is transferred in that plane. The casting machine has balanced forces in which both plates and mold halves or dies are moved equal distances to and from the part plane and this balanced movement of mass cancels out the normal shock of starting and stopping heavy plates and tools, equalizes thermal expansion differences and automatically centers load deflections.